Unitized Regenerative Fuel Cells for Hydrogen Energy Storage Systems. Hiroshi Ito, Akihiro Nakano

Transcription

1 Japan-Norway Energy Science Week 2015 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 1 Unitized Regenerative Fuel Cells for Hydrogen Energy Storage Systems Hiroshi Ito, Akihiro Nakano National Institute of Advanced Industrial Science and Technology (AIST) Naoki Miyazaki, Masayoshi Ishida University of Tsukuba

2 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 2 Outline 1. Background / Scope 2. R&D on Unitized Regenerative Fuel Cell (URFC) 3. R&D on Hydrogen storage with metal hydride 4. Summary

3 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 3 A Synergy between Hydrogen and Electricity Grid Connected RE-Hydrogen System Hydrogen may be used as fuel in almost every application where fossil fuels are being used today. Hydrogen is useful as an energy carrier, because energy storage density is significantly high with compressed form, liquefied form, or metal hydride. Grid Independent RE-Hydrogen System From sustainability point of view, a synergy between hydrogen and electricity and renewable energy sources is particularly promising. Hydrogen production with water electrolysis must be suitable for renewable energy sources.. F. Barbir, Solar Energy 78 (2005) pp

4 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 4 Totalized Hydrogen Energy Utilization System (THEUS) Hydrogen station To enhance the versatility of hydrogen energy in the industrial, the commercial, and the transportation sectors through THEUS.

5 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 5 Outline URFC and MH tank have been evaluated as key components of hydrogen energy system in stationary applications. A bench-scale URFC was installed and would be evaluated as an energy conversion system. MH tank was developed by own and evaluated in a long time operation. In particular, we have been focusing on the thermal energy recovery from the both operations of URFC and MH tank.

6 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 6 Overview of Unitized Reversible Fuel Cell (URFC) URFC System Advantages Power Input Water Electrolyzer (Ely) Pure Water URFC Fuel Cell (FC) H 2 H 2 Hydrogen Storage Unit O 2 /Air Power Output Heat Long-term and large quantities of energy storage compared to current secondary batteries. Continuous running permits to make a rate of operation double compared to individual use of FC and Ely. Acquisition of oxygen as by-products Electrolysis Overall : H 2 electrode (cathode) : O 2 electrode (anode) : Fuel Cell Overall : H 2 electrode (anode) : O 2 electrode (cathode) : Cell reactions H O( l) H ( g) + 1/2O ( g) H + 2e H 2( g) + 2 l 2 H O( ) 2H + 1/ 2O ( g) + 2e H ( g) + 1/2O ( g) = H O( l) H ( ) 2H 2e 1/ 2O ( ) 2H 2e H O( l) g g Possible applications Hydrogen energy storage system for load leveling at buildings Remote hospital Lake water purification Remote UPS system

7 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 7 Installation of a bench-scale URFC URFC stack DC Load DC Power DI water supply Inside Chiller Overview Installed in March 2014 Supplied from Takasago Thermal Engineering Co.

8 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 8 Specifications of bench-scale URFC System Electrolysis operation Fuel cell operation Input power (rated) 4.5 kw Gas production rate H 2 : 1.0Nm 3 /h, O 2 : 0.5Nm 3 /h Gas pressure H 2 : 0.9MPa(G)_max, O 2 : Atmospheric Power output (rated) 0.8 kw H 2 utilization >90% H 2 pressure <0.05MPa(G) Cell/stack Membrane Nafion 115 Electrocatalyst H 2 side Pt O 2 side Pt/Ir-black Active area 250 cm 2

9 Schematic draw of gas/liquid flows around URFC Chiller Pump-1 Circulation pump BLW Blower H 2 Air Pump-3 Circulation pump Membrane humidifier Chiller H 2 B Chiller Air / O 2 Chiller DI water Water purifier Gas (H 2 )-water separator Pump-2 Circulation pump Gas (O 2 )-water separator Water drain Component Rated power consumption Cooling water pump (Pump-1) 90 W Water circulation pump (Pump-2) 60 W H2 circulation pump (Pump-3) 26 W Air blower (BLW) 500 W Hydrogen is recirculated. Air is humidified using a membrane humidifier. H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 9

10 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 10 Electrolysis operation - i-v characteristics At 40 C At 60 C kpag(40 C) kpag(60 C) Cell stack voltage [V] kpag(40 C) 0 kpag(40 C) Cell stack voltage [V] kpag(60 C) 0 kpag(60 C) Current density [A/cm 2 ] Current density [A/cm 2 ] The effect of temperature on the performance was relatively large, while the effect of pressure was small.

11 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo Fuel cell operation Cell stack voltage [V] C 60 C Current density [A/cm 2 ] The cell/stack performance was significantly influenced by the operating temperature, which should be higher than 60 C.

12 Continuous operation 75 Cell temp. H2 pressure 0.9MPa 100A Current Voltage Cell temp. 22V V Voltage Current 250A Fuel cell mode Electrolysis mode Switching Switching (ca. 5min) Since the operation interface was well-organized, the system could be operated and switched easily. Switching time was 5-10 min. H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 12

13 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 13 Experimental set-up of MH tank Metal hydride bed in AIST Schematic of the experimental set-up

14 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 14 Metal Hydride Tank (Metal hydride alloy) - Japanese version - Composition: MmNi 5 Total weight: 50 kg Size:500 μm Reaction heat h Absorption: kj/molh 2 Desorption: kj/molh 2

15 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 15 Individual absorption/desorption test results P-C isotherm Absorption Desorption Operating conditions (Absorption: 9 hour) H2 flow rate: 11.0 NL/min Circulation water : 32, 1.12 l/min (Desorption: 13 hour) H2 flow rate: 7.6 NL/min Circulation water : 12, 0.46 l/min Q cw = 6.84 MJ, ε = 89.4 % Q cw = 6.62 MJ, ε = 89.8 % Recoverd thermal energy from coolant: Q cw Reaction heat recovery rate:ε = (Q cw /Q MHreact ) 100 H/M= MH utilization ratio: 94% GH 2 : 5920 NL Q MHreact = V H2 h

16 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 16 Absorption-desorption continuous test results (a) P-C isotherm (b) Temperature of coolant Reaction heat recovery rate, ε Day1 AB 87.4 % DS 73.3 % Day2 AB 75.4 % DS 72.5 % Day3 AB 76.2 % DS 72.3 %

17 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 17 Summary In this study, we investigated the performance of URFC and MH tank as key components of hydrogen storage system. The bench-scale URFC could operated quite successfully. The performance of each operation mode in URFC was comparable with that of individual apparatus of PEM electrolyzer and PEMFC. MH tank was developed and tested in daily cycle operation. Reaction heat recovery rate was excellent as over 70 %. The connection between URFC and MH tank was completed, and consolidated test is ongoing.

18 H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 18 Thank you very much for your attention! Hiroshi Ito